US 6,153,157 AGranted

Value improvements of clays

AssigneeMcLaughlin Geosurveys Pty. Limited

InventorRobert Joseph McLaughlin

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Abstract

A process which allows the conversion of clay minerals of the kalonite group, to a relatively pure form of alumina and silica respectively comprising the steps of (a) heating the kaolinite group minerals to greater than 500.degree. C., which causes dehydroxylation of the crystallographic lattice and formation of an intermediate meta-kaolin; (b) reacting the intermediate with only one of a selection of reagents including acids, alkalines or metalliferous compounds followed by heating of the mixture to form an aluminium salt in solution and residue of silica; (c) separation of the aluminium salt solution from the residue of silica by filtration and further treatment of the silica residue to produce a relatively pure form of fine particled silica; (d) formation of an alum by addition of ammonium sulphate in solution to the aluminium salt solution and further treatment of the alum to produce a relatively pure form of aluminium hydroxide.

Claims19

Dependent claims

A process for converting clay minerals of the kaolinite group to a substantially pure form of aluminum hydroxide and silica, respectively, comprising the steps of:

(a) heating clay minerals of the kaolinite group to a temperature greater than 500.degree. C. for causing a dehydroxylation of a crystallographic lattice and forming an intermediate meta-kaolin;
(b) reacting the intermediate meta-kaolin with sulfuric acid thereby forming a mixture of meta-kaolin/sulfuric acid;
(c) heating the mixture of meta-kaolin/sulfuric acid to form an aluminum salt solution and a residue of silica;
(d) separating the residue of silica from the aluminum salt solution via filtration;
(e) purifying the residue of silica obtained in said step (d) for obtaining a substantially pure form of fine particle silica;
(f) adding ammonium sulfate to the aluminum salt solution remaining after said step (d) for forming an alum solution;
(g) cooling the alum solution so that alum crystallizes therefrom;
(h) separating alum that crystallized in said cooling step from the alum solution via filtration;
and,
(i) purifying the alum obtained in said step (h) for obtaining a substantially pure form of aluminum hydroxide.

7 more elements

Dependencies are inferred from the claim text.

Facts

Application: 09/214,584Filed 31 Dec 1998
Priority: AU PO 264030 Sep 1996
Granted: 28 Nov 2000
Term ends: Not estimatedThe source records don’t support an estimate.

Classification9 codes

C01F 7/765
Ammonium or alkali metal aluminium sulfates: ammonium aluminium sulfates
C01B 33/187
Preparation of finely divided silica neither in sol nor in gel form; After-treatment thereof: by acidic treatment of silicates
C01F 7/20
Aluminium oxide; Aluminium hydroxide; Aluminates: preparation of aluminium oxide or hydroxide from aluminous ores using acids or salts
C01F 7/26
Preparation of aluminium oxide or hydroxide from aluminous ores using acids or salts: with sulfuric acids or sulfates